Process of preparing paper pulp



Patented June 28, 1927.

UNITED STATES I FREDERICK KNAPr FISH, In, or sax rmncrsco, cALu'oaNm.

PROCESS OF PREPARING PAPER PULP.

No Drawing. Application filed May 24, 1926, Serial No. 111,368, and in Canada July 7, 1925.

I have described certain processes for the treatment of plant material in which solvent extractives of the material are used in the processes for attacking the binding and intercellular constituents of the material in order to liberate the fibre, both with and wvithout the addition of further chemical reagents.

The present invention relates to a further development in the art of producing pulp and has for 1ts main object the reduction of the cost of the production of pulp of a therein to remove air standard or improved quality.

I have found that the addition of sulphur to the liquor applied to the chips produces very desirable results in hastening the cook and in some manner, which I am unable at present to fully explain, improves the condition of the fibreot the cooked material and the color of the pulp produced therefrom.

In carrying out my process the chips are charged into the digester' where they are treated with a liquor to which sulphur is added. The liquor is preferably initially charged with volatile and other solvent exwood and the desired chemical reagent. such as soda, caustic potash, lime and the like is added. The sulphur may be dissolved directly in the liquor or it may be previously dissolved in a suitable solvent and then added to the liquor. I have found it satisfactory in some treatments to charge the sulphur directly into the digester prior to or during the period of supplying liquor to the charge. In such cases the sulphur appears to be distributed through the contents o1 the digester to disso ve in the liquor and otherwise act on the chips to effectively treat the same so as to soften. dissolve and remove or distribute the resins, lignin and other constituents which surround the wood fibre so that the cooked charge is in the desired condition for further treatment.

During the charging operation the liquor is preferably circulated and sprayed on the chips to assistand hasten the saturation of the chips with the liquor. VVhen'the digester is completely charged a vacuum is produced from the charge and a vacuum of 15 or 20 inches is maintained for tractives of Patent,

a limitedperiod. During this stage of the process the circulation and spraying of the liquor is preferably continued. The full charge of, iquor is then admitted to the diester and the temperature is raised to complete the cook.

I have thus been enabled to considerably reduce the time required for cooking the wood and the pulp produced has a tough fibre and improved color.

While as previously stated I am not prepared to assign a definite reason for the beneficial results by the treatment herein described, it is to be noted that the reactions between the sulphur and other constituents of the liquor take place in contact with or in the wood chips and all of the products of reaction are thus free to act on the binding constituents'of the wood fibre. lVith liquors prepared prior to charging the same into the chips in the digester the reactions mentioned do not take place in contact with the chips. It is possible that this may be to some extent responsible for the improved results obtained, but obviously to limit this invention to any particular theory which may underlie the operation of the'process.

What I claim is:

1. A process .of producing pulp which consists in cooking chips in a digester with a liquor containing solvent extractives of plant material to which sulphur has been added.

2. A process of producing pulp which consists in cooking chips with a liquor charged I .do not wish with volatile and other 'extractives of plant inaterial and in which sulphur is incor- 6. A process of makingpulp which conprocess of producing pulp which si-sts in cooking chips in a diester with a liquor initially contamin e emental sul- Ehur, solvent extractives 0 wood and an alali and. utilizing in the cook, products of 'sulphui', chemical reagent which will unite with the sulphur, and added extractives of wood, the sulphur reagent and extractives being free to react with or on the binding constituents of the chips during theprogre'ss of the reactions.

8. A process of producing-pulp com rising mixing elemental sulphur with a cl iemical reagent in the absence of air'and treating chips in a digester with liquor so roduced and maintained free from atmos Here to'cause such liquor to react with the binding constituents of the chips to so act on the chips as to permit the liberation of the fibre in the cook.

In testimony whereof I aflix my signature.

FREDERICK KNAPP FISH, JR. 

